I've bagged in both the paper bags and in 39 gal lawn/leaf bags. Neither is ideal.
You can't fit much in them unless you stomp them down every time you dump some in and that takes time to do - LOTS and LOTS of time. If you don't compress them, it's a waste of time/money in my opinion.
I have one of those cardboard funnels, but didn't like it because I couldn't shove my foot in the bag to compress the leaves.
Ultimately, bagging leaves is a homeowner task. You can not bag leaves and make any money - it takes too long.

Hauling. Almost as bad. My trailer is small and it fills up FAST. It's 5x8 and has sides about 2.5' high which helps, but leaves take up a lot of space unless compacted. I always take a sheet of plywood and when I have it half full I toss the plywood on and walk around on it to smash them down making room for more.
Hauling limits me to small properties.

Curbside pick up is where it's at. No bags, no hauling, no hassle.
I don't do enough leaves to justify a vacuum.

I'm sorry if I was ambiguous in my posts about bagging leaves. NO -- not a fan of bagging leaves!!!!

I have three properties that cause me to raise the question. Two are similar, in that they have many leaves from maple and oak trees. The leaves of these trees are mulched and left at the property. But, both properties have Ginkgo trees, a large one at each property. Ginkgo leaves usually fall when still a pale green, not dry, leathery, and very tough. They are impossible to mulch. They must be taken off in some way. A full bag of Ginkgo leaves is too heavy to carry -- they are unlike any other leaf. In the past, I have had 4-6 bags of Ginkgo leaves off each of these properties, and expect the same this season.

The other property does not have many leaves on the developed part of the property around the house. But, the area has lots of beds, most of which have pachysandra ground cover. Behind the house are heavy woods, with many large oak and maple trees. This wooded area is upwind from the house area, and these leaves find their way into the beds and ground cover in a huge way. Last season, I took the leaves far back into the woods to dump. The owners claimed (wrongly in my estimate) that the leaves from my piles blew back into the beds. They want me to "take them away" this season. My choice is to use a different trailer to tarp them and haul them out, or to bag them, and leave them for the owner to put to the curb for township pickup. I expect 20 bags over about 5-6 cleanups. There is very little turf area on the property (only takes me 45 minutes to mow with hand mower), so mulching them on the turf is out of the question. I really don't want to make 5-6 trailer trips to the dump for a few tarps of leaves each time. This is how I got to the bagging solution for this property.

I have many, many other properties with lots, lots, and more lots of leaves. The 20 bags represents a very small sliver of leaf control for me. I'm sorry if I confused, and left the wrong impression.